Device for a business machine

ABSTRACT

A memory device in a cash register keyboard including resilient means cooperating with memory slides to prevent setting of these slides until a machine cycle initiating key is entirely depressed. This is accomplished by the resilient means (leaf springs) being connected to the memory slide and being forced to bear against a stopping means until said key is entirely depressed. The stopping means is withdrawn from the moving path of the springs by starting the machine. By this arrangement, it is impossible to enter incorrect information in the cash register by displacing memory slides before a machine cycle has been started.

[ 1 June 27, 1972 United States Patent Mattsson et al.

2,854,190 9/l958 3,l94,496 7/1965 Bullock................................,23S/l3O 3,464,623 9/1969 Busch Goran Lindelow, Taby, both of Sweden [73] Assignee: Svenska Dataregister AB, Solna, Sweden Primary Examiner-Stephen .I. Tomsky March 13, 1970 Attorney-Norman Friedman, Stephen E. Feldman, Arthur T. Groeninger, Morris 1. Pollack and Philip Furgang [22] Filed:

[2]] Appl. No.:

[30] Foreign Application Priority Data March 20,1969

tirely depressed. This is accomplished by the resilient means (leaf springs) being connected to the memory slide and being forced to bear against a stopping means until said key is entire- 6 m. 0/ 3B 0 5 awn 2 a 9,c.9 1M 0 6 M q 5 3 3 2 mm a 2 M d and h ly depressed. The stopping means is withdrawn from the mov- Rderences (med ing path of the springs by starting the machine. By this ar- UNlTED STATES PATENTS rangement, it is impossible to enter incorrect information in the cash register by displacing memory slides before a m s S b w a h e I c y c e .m h C a m 2,561,552 Anderson Sundstrand........,..................

DEVICE FOR A BUSINESS MACHINE The present invention relates to a device in a business machine and more particularly to a memory device in its keyboard.

The devices described below as examples of an embodiment of the present invention intend to meet the increased requirements of quickly and safely perfonning memory functions in the keyboard of a business machine.

Known devices for performing memory functions in business machines usually consist of a system of memory slides whose purpose is to memorize the operations performed during one or several machine cycles in order to control the following operations in a desirable way. The memory slides are set in different positions by keys arranged on the keyboard of the machine whereby the relocation of one or several memory slides cause other memory slides to change position and perfonn the memory and or blocking functions, whereby the following machine operations are controlled. The memory slides affected by the keys are usually provided with recesses with varying configuration turned towards the keys, by which, when depressing the keys, the memory slides receive a longitudinal movement which is transferred to memory slides in other banks in the keyboard via intermediate positioned slides. Since also the last mentioned memory slides are provided with recesses with varying configuration, certain of the keys positioned above these will at one or several following machine operations be blocked from being depressed. It is also possible to let the memory slides in one bank perform blocking and memory functions within the same bank.

However, the above described previously known memory devices exhibit the disadvantage that they by careless handling of the machine can be affected to take up incorrect positions, thereby causing incorrect information to be accumulated in the machine. Such careless handling can be that the machine is affected to take up a position other than its normal position which is a position where the machine stands on an essentially horizontal surface whereby the memory slides depending on their mass or depending on the mass of the means connected to the memory slides, by the gravity, can be moved to a position which is incorrect for the following operation. Furthermore, careless handling can be that the machine is subjected to shakings or hits which can cause movement of the memory slides to the effect that a following operation can be erroneously performed. A further handling of the cash register, which can bring about that the memory slides are set in incorrect positions, is that the operator of the machine knowingly or unknowingly depresses or quickly taps one key, positioned above a memory slide, half-way and thereafier permits the key to be restored to a not depressed position whereby the machine is not permitted to start. In this way, the last mentioned memory slide will be moved with the result that a following machine operation which is initiated by another key, can be performed in an incorrect way.

With these disadvantages in mind the present invention refers to a device which prevents incorrect information from being accumulated in a business machine because of careless, or knowingly or unknowingly erroneous handling of the same. This is obtained by resilient means which cooperate with the memory slides and which prevent the setting of the memory slides until any key on the keyboard of the machine which initiates a machine cycle is depressed. Blocking means which cooperate with the resilient means and which constitute a support for the resilient means before and when a starting key is depressed, receive a reciprocal movement initiated by the depressed starting key so that the resilient means cooperating with the memory slides which are to be set are released and affected by the blocking means to take up positions wherein the corresponding memory slides are in a set position.

According to this the present invention refers to a device for moving blocking means, for example memory slides, positioned in a business machine which is mentioned in the introduction to claim one, and the characteristics of the invention are evident from the characterizing parts of the claims.

In order to understand the units included in the device, their functions and the connection between these units, it is referred to the following detailed description in connection with the accompanying drawing which shows a perspective view of the device according to the invention included in a business machine such as a cash register.

The device shown in the FIGURE exhibits a particular embodiment of the present invention which only includes as many units as necessary to make the principles of the present invention quite clear. For instance, in the diflerent banks only a few keys and memory slides, respectively, are shown but it is to be noticed that for example each selector bank can include up to nine keys and three memory slides and the operation bank can include five memory slides. Even the number of the memory links can exceed the number shown in the figure.

The particular embodiment of the present invention shown in the FIGURE includes three keys 2, 4 and 6, positioned in the selector banks, each key being fixed to one keyshafi 8, l0 and 12, which extend downwards through slots in a lower keyboard plate 13, one slot for each keyshaft. In the figure only the slot 13a which corresponds to keyshaft 12 is shown. Actuators (not shown), affected when any of keys 2, 4 or 6 is depressed are positioned below keyboard plate 13 within the machine. Keyshafts 8, l0 and 12 are provided with rectangular slots l4, l6 and 18 through which memory slides 20, 22 and 24 are extending. Memory slides 20, 22 and 24 extend through each key-shaft 8, l0 and 12 positioned in respective selector bank and are supported and guided by supports 1, 3, 5 and 7 which are formed particularly for the memory slides 20, 22 or 24 and which will be described more in detail below. Recesses 22a, 22b, 22c, 22d, 24a, 24b, 24c and 24d are formed on the upper sides of memory slides 20, 22 and 24 which in case they are positioned directly below any of keys 2, 4 or 6 pennit depression of this particular key. If a memory slide 20, 22 or 24 does not have a recess 22a, 22b, 22c, 22d, 24a, 24b, 24c or 24d positioned below any of keys 2, 4, or 6 this key 2, 4 or 6 can not be depressed but will be blocked by the upper edge of this memory slide 20, 22 or 24. Recesses 22a, 22b, 22c, 22d 24a, 24b, 24c and 24d have irregular and among themselves varying shape whereby different operations are obtained when any of keys 2, 4 or 6 is depressed. Recess 24b is a significative example of the form of a recess. To the right in the figure recess 24!; consists of a first part 24c which inclines towards the horizontal plane, which in case it is positioned below the keyshaft 8, when this is depressed, will be affected by the upper edge of its recess 14 and be moved to the right whereby the memory slide 24 also is moved to the right. To the left in the figure recess 24b has a second part 24f which also inclines towards the horizontal plane which, however, never will be affected by keyshaft 8. In case no movement of memory slides 20, 22 or 24 is required, recesses 22a, 22b, 22c, 22d, 24a, 24b, 24c and 24d are provided with such a horizontal extension that keyshafts 8, l0 and 12 when depressed do not affect memory slides 20, 22 and 24.

Memory slides 20, 22 and 24 are in their to the right in the figure turned ends connected to horizontal, rockable memory links 26, 28 and 30 positioned perpendicularly to them, which connect memory slides 20, 22 and 24 with memory slides 32 and 34 positioned in the operation bank.

Memory slide 20, which is not necessary for the visualizing of the operation which will be described below but only has been shown for the purpose of showing that more than one memory slide can be included in a selector bank and that a selector bank can include keys which represent different categories (keys 4 and 6), is only in engagement with memory link 30 via a recess 20: provided on the memory slide 20. The other memory slides 22, 24, 32 and 34 are also provided with one recess 22:, 24k, 324' and 34 each by which they are in engagement with one of memory links 26, 28 or 30. lt is apparent from the figure that memory slides 22, 24 and 32 are only in engagement with memory link 26 and that memory slide 34 is only in engagement with memory link 28.

Memory slides 32 and 34 in the operation bank are parallel with memory slides 20, 22 and 24 in the selector bank and are like these supported by supports 46 and 48, preferably made of plastic and attached to the lower keyboard plate 13. Plastic supports 46 and 48 are provided with vertical walls 46a, 46b, 46c, 48a, 48b, and 480, between which memory slides 32 and 34 extend, and horizontally positioned rollers 50 and 52 movably supported in supports 46 and 48 and against which rollers 50 and 52 memory slides 32 and 34 bear. Rollers 50 and 52 are made of steel and are arranged in order to decrease the friction between memory slides 32, 34 and plastic supports 46, 48. Memory slides 32 and 34 extend, like memory slides 20, 22 and 24, through slots 54a and 58a provided in key shaft 54, 56 and $8. in order to permit further memory and other slides to be included in the operation bank also slots 54b, 26 b and 58b in key shafts 54, 56 and 58 are arranged. In the figure, for the sake of cleamess, only key shafts 54, 56 and 58 are shown but these are, of course, provided with keys similar to keys 2, 4 and 6 positioned in the selector banks. Key shafts 54, 56 and 58 extend downwards through slots 13b, 13c and 13d in the below positioned keyboard plate 13 and affect, when depressed, actuators (not shown) positioned in the machine. In order to permit key shafts 54, S6 and 58 to be depressed, memory slides 32 and 34 as well as memory slides 20, 22 and 24 are provided with recesses 32a, 32b, 320; 34a, 34b, 340, which are shaped in a similar way as the recesses in memory slides 20, 22 and 24.

Memory links 26, 28 and 30 are in their respective ends via therein shaped rectangular protrusions 26a, 28a and 30a, rockably supported in dovetail formed slots 36a, 36b and 36c in two general plates 36 and 38. Protrusions 26a, 28a, 30a on memory links 26, 28, 30 and dovetail shaped slots 36a, 36b, 36c in general plates 36 and 38 are shown in the drawing only in connection with general plate 36, but memory links 26, 28 and 30 are, of course, supported in the other general plate 38 in a similar way. General plate 36 is attached to an ear 42, which is provided on the lower positioned keyboard plate l3, with a locking pin 44. General plate 38 is attached in a corresponding way.

Each of memory links 26, 28 and 30 are in their lower right ends provided with a leaf spring 60, 62 and 64 which is rivetted, by rivets 67 and 68 on a respective memory link. Leaf springs 60, 62 and 64 extend through a rectangular slot 36d which is provided in general plate 36 and leaf springs 60, 62 and 64 rest with their outer ends against one side on a vertical protrusion 66a, 66b, 66c. Protrusions 66a, 66b and 66c are arranged on a vertical arm 66 which receives an upwardsdownwards movement during a machine cycle. Each recess 66a, 66b, 66c is beveled in its upper part and thereby constitutes two towards each other standing inclining planes 66d, 66:, 66g, 66):, 66:, 66f.

The task for leaf springs 60, 62 and 64 is to prevent memory links 26, 28 and 30, and thereby memory slides 20, 22, 24, 32 and 34 because of external violence such as affection of any key by a rapid blow, from being set in an, incorrect position and remain in this position. This incorrect setting can not be performed since arm 66 on which protrusions 66a, 66b and 66d are provided and against which protrusions leaf springs 60, 62 and 64 are resting is not moved downwards if none of keys 2, 4, 6, 54, 56 or 58 are completely depressed and thereby start the machine cycle. This will be better understood from the description of arm 66 and its connection to main shaft 78 in the machine. Thus, leaf springs 60, 62 and 64, if one or several of memory slides 26, 28 or 30 by external violence are caused to take up an incorrect position, will restore the memory slides to their original home position as soon as the external affection has ceased. IT is to be realized that the pressure of leaf springs 60, 62, 64 against protrusions 66A, 66B, 666 is performed essentially in the same way as well during clockwise as during counter clockwise rotation of memory links 26, 38, 30. The difference is only that when a memory link 26, 28 or 30 is rotated clockwise its leaf spring 60, 62 or 64 will rest against the right side of protrusion 66a,

66b or 66c and when the same memory link 26, 28 or 30 is rotated counter clock-wise leaf spring 60, 62 or 64 will rest against left side of protrusion 66:, 66b or 66c. Vertical arm 66 is in its lower end rotatably connected to an additional arm 68 with a rivet 70. Arm 68 is, with a screw 72, rotatably supported on a frame 74 in the machine and provided with a roller 76 which rests against a cam attached to main shaft 78 in the machine. Cam 80, when in its home position, takes up such a position that roller 76 rests against an outer periphery 800 on cam 80 whereby arm 66 is positioned in its upper position as shown in the figure. When the machine is started and main shaft 78 is turned counter clockwise roller 76 continues to rest against the outer periphery 800 during the first 10 of the rotation but will thereaher rest against an inner periphery 80b on cam 80 whereby arm 66 is moved downwards until cam 80 has been rotated such a long distance that the outer periphery 80a again has taken up a position straight in front of roller 76, when the outer periphery 80a and roller 76 again will make contact, whereby arm 66 is moved upwards again. The contact of roller 76 against cam 80 is performed by a compression spring 86 positioned below a fixation bracket 84 which in turn rests against the upper part of arm 66. Compression spring 86 affects, irrespective of the position of main shaft 78 in the machine, via arms 66 and 68, roller 76 to rest against periphery 80a or 80b of cam 80. This will appear more clearly below in connection with the description of fixation bracket 84 and its function. Arm 66 is provided with a recess 66] which surrounds a screw 82 which is fixed to frame 74 whereby arm 66 is controlled for vertical, reciprocal movement.

Fixation bracket 84 retains memory links 26, 28 and 30 in the positions they take up after the depression of a key. Fixation bracket 84 is provided with two vertical parts, of which only one is shown. The other vertical part is identical with the shown part 84a and operates in the same way, and is positioned straight opposite this one on the opposite end of fixation bracket 84. The vertical part 840 extends downwards through a hole 13c which is cut out in lower keyboard plate 13 and the vertical part 84a is rotatabiy supported around right edge l3fof hole 13c. The supporting is performed by an essentially semi-circular recess 84b arranged in part 840 and whose edges bear against the lower keyboard plate 13 on both sides of the same. In the figure the upper one 84c of these edges is shown. Fixation bracket 84 is provided, partly with a horizontal part 84d, which rests against the upper edge of arm 66, partly a similarly horizontal part 84a, provided with recesses and protrusions, of which only a few 84] and 84g together with 8411 and 84: are shown. The above mentioned compression spring 86 is positioned below part 84c and is attached to this with one of its ends. Compression spring 86 is in its other end attached to the lower keyboard plate 13. When arm 66 is positioned in the upper position which is shown in the figure, it pushes the horizontal, to the right positioned part of fixation bracket 84d upwards, whereby the horizontal, to the left position part 84 of fixation bracket 84 is pushed downwards, which in turn brings about compression of compression spring 86. When the inner periphery 80b of cam 80 is positioned straight opposite roller 76 part 84c is forced upwards by compression spring 86 and part 84d is thereby forced downwards whereby arm 66 receives a downwards movement, whereby protrusions 84h and 841', together with the other protrusions (now shown in the figure), are raised so that they will be positioned on both sides of memory links 26, 28 and 30, respectively, and fix these in their, during the machine cycle, earlier received positions.

In order to further visualize the units included in the device, their functions and the purpose with these functions, an operation which is practicable by assistance of the units shown in the figure, will be described below. This operation visualizes i. a. the method of proceeding when accumulating an amount which relates to taxable articles and the thereafter following accumulation of the tax charge in the machine. For this purpose a key for taxable articles is arranged in the mode of operation bank, in the figure represented by key 58. The depression of the key for taxable articles 58 can be performed before the depression of the amount keys as key 58 does not have a starting effect. Besides accumulation of the amount in a totalizer represented by key 58, this amount is also accumulated in a department totalizer, which totalizer is represented by key 4 or 6. A total key for taxable articles, on the figure represented by key 56 is arranged in the mode of operation bank. This key which has a starting effect performs, when depressed, that the totalizer for taxable articles is zeroized and the total which is taken out of this totalizer is transferred to a Grand Totalizer (not shown). A tax key is positioned in one of the selector banks in the figure represented by key 2. After amount keys corresponding to the total tax amount have been depressed, key 2 is depressed whereby the total tax amount is accumulated directly into the Grand Totalizer (not shown). As mentioned above there are department keys, in the figure represented by keys 4 and 6, which represent different departments and which when depressed, performs that an amount previously depressed on the amount banks is accumulated in certain department totalizer arranged for respective department. ln order to make a total taking operation possible, a total key is arranged, in the figure represented by key 54, in the mode of operation bank. In case an amount is to be accumulated in the machine, which amount relates to taxable articles, the key for taxable articles 58 must be depressed before any of department keys 4 or 8 is depressed This procedure is necessary and made possible since each key shown in the figure 2, 4, 6, 54 and 56 except for the key for taxable articles 58 has a starting effect, i. a. starts the machine cycle. When the key for taxable articles 58 is depressed memory slide 34 is affected to be moved to the right whereby it blocks total key 54 so that the total taking operation can not be performed on the immediately following machine operation. It is to be noticed that it must be impossible to perform a total taking operation directly after a taxable amount has been accumulated in the machine as a total taking operation merely for taxable articles and the subsequent accumulation of the tax charge must be performed first. Total key for taxable articles 56 can be depressed on a following machine operation as a total taking operation for the taxable articles must be possible to perform at this occasion. Furthermore, memory slide 34 affects, when moved to the right, memory link 28 to be pivoted counter clockwise. As memory link 28 is not in engagement with any other memory slide but memory slide 34, the other memory slides 20, 22,24 and 32 remain unaffected during the above described operation.

Both before and after accumulation of amounts which relate to taxable articles, amounts that relate to non-taxable articles can be accumulated in the machine. These amounts will, on the condition that the key for taxable articles 58 has not been depressed, when depressing any of department keys 4 or 6, be accumulated in each department totalizer and in the Grand Totalizer.

When a total taking operation for taxable articles is to be performed, for zeroizing the corresponding totalizer and transferring the amount contained in this totalizer to the Grand Totalizer, total key for taxable articles 56 is depressed. The figure shows the units included in the device in the position they have taken up after depression of the total key for taxable articles 56. In the figure total key for taxable articles 56 has affected memory slides 32 and 34 to be moved to the left, whereby the blocking of total key 54 now is performed by memory slide 32. According to the reasoning above, total key 54 still must be blocked as a total taking operation, when amounts which relate to taxable articles have been accumulated in the machine, must be impossible to perform before the total tax amount has been accumulated in the machine. The accumulation of the mentioned tax amount requires a depression of tax key 2, which will be described in more detail below.

The movement of memory slide 32 is transferred to memory slides 22 and 24, positioned in the selector banks via memory link 26 whereby department keys 4 and 6 are blocked. Thus, on the following machine operation only tax key 2 can be depressed as, after the total taking operation for taxable articles, it must be impossible to accumulate additional amounts in the department totalizer before the tax has been accumulated in the Grand Totalizer. After the tax amount has been accumulated, which is performed by depressing keys positioned in the amount banks, tax key 2 is depressed whereby the accumulated tax amount is accumulated in the Grand Totalizer. When depressed, tax key 2 also affects memory slide 24 to be moved to the right once again whereby memory link 26 is pivoted counter clockwise and restores memory slide 32 to the position it assumed before key for taxable articles 58 was depressed, whereby the blocking of total key 54 is released and a total taking operation can be performed. On a following depression of total key 54 the Grand Totalizer and the total amount which is positioned in the same is transferred to the printing means and indicators (not shown) in the machine. As mentioned above, memory links 26, 28, 30 are each provided with a leaf spring 60, 62, 64, the task of which is to prevent any of memory slides 20, 22, 24, 32 or 34 from taking up a position which is incorrect for the continued operation of the device and to remain in this incorrect position, which could be caused by external violence, such as taps or blows on any key or on the business machine itself or when depressing any of keys 2, 4, 6, 54, 56 or 58 half way. It was also mentioned before that leaf springs 60, 62, and 64 rest against protrusions 66a, 66b and 66c of arm 66 when it is in its upper position which is the case when no machine cycle has been started. This means that memory links 26, 28 and 30 and thereby memory slides 20, 22, 24, 32 and 34, when trying to take up positions which are incorrect for the continued operation of the device, immediately afier the attempt to perform an incorrect setting has ceased, are pivoted back to their respective home positions by leaf springs 60, 62 or 64 as these rest against protrusions 66a, 66b, 660 the whole time. In order to allow leaf springs 60, 62 and 64 to pivot and to follow respective memory link 26, 28 or 30 when they pivot, it is necessary that arm 66 is moved downwards, which is performed when a machine cycle is started and main shaft 78 is turned counter clockwise. Protrusions 66a, 66b and 660 are thereby moved so far downwards that leaf springs 60, 62 and 64 no longer rest against these but follow their respective memory links 26, 28 and 30 and take up positions where the leaf springs are not bent. Protrusions 66a, 66b and 66c will, after main shaft 78 has been rotated about and arm 66 has been restored to its upper position, take up their original position whereby the leaf springs that have been bent earlier during the machine cycle, i. a. the leaf springs which are attached to affected memory links, will be positioned on the other side of the protrusions which they were in contact with on the beginning of the machine cycle.

For example, when depressing key for taxable articles 58, memory link 28 is pivoted counter clockwise, but as key 58 has not a starting effect, arm 66 will remain in its upper position and leaf spring 62 which is attached to memory link 28 continues to rest against the left part of protrusion 66b until some of department keys 4 or 6 is depressed and a machine cycle is initiated, whereby arm 66 and thereby also protrusion 66b are moved downwards. Not until then leaf spring 62 will take up a position corresponding to the position taken up by memory link 28. On a following depression of total key for taxable articles 56 both memory link 26 and 28 are pivoted clockwise and as key 56 has a starting effect, arm 66 and its protrusions 66a, 66b and 66c are moved downwards whereby leaf springs 60 and 62 also are pivoted clockwise. Thereafter, arm 66 receives a movement upwards so that protrusion 66a and 66b take up positions on the other side of leaf springs 60 and 62. When depressing tax key 2, a counter clockwise turning of a memory link 26 is performed in a corresponding way. Arm 66 and thereby also its protrusions 66a, 66b and 66:" also receive downwards and following upwards movement in a corresponding way, whereby leaf spring 60 takes up a position corresponding to the position taken up earlier by memory link 26.

When arm 66 is positioned in such a position that leaf springs 60, 62 and 64 no longer rest against their respective protrusions 66a, 66b or 66c, the protrusions arranged on the left part 84c on fixation bracket 84, of which only protrusions 84!: and 844' are shown, are positioned in contact with and fix memory links 26, 28 and 30 in the positions they have assumed earlier during the machine cycle. This means that memory links 26, 28 and 30 always will be fixed in their positions during the central part of a machine cycle independent of it they have or have not been affected earlier, why it, according to the above mentioned, is impossible to affect the machine by external violence and thereby perform incorrect accumulation of information in the same.

It is to be pointed out that the described embodiment only intends to illustrate the invention which is not limited by this description but only by the scope of the appended claims.

We claim:

1. A device for preventing blocking means in a business machine from assuming a second position which is separated from a first position comprising at least one pivotable resilient means which is connected to the blocking means a stopping means arranged in the path of movement of the resilient means and mounted so that when the blocking means is affected to take up the second position the resilient means biases it to bear against one side of said stopping means and which stopping means restores the blocking means when the mentioned affection ceases.

2. The device of claim 1, wherein there are a plurality of blocking means and wherein certain of the blocking means cooperate with each other via rockable links.

3. The device of claim 1 wherein the blocking means when they are in certain positions block certain keys, positioned on the keyboard of the machine, against depression.

4. The device of claim 2 wherein the resilient means consist of leaf springs which are fixed to links.

5. The device of claim 4 wherein the stopping means are formed on an arm which is capable of performing a reciprocal movement and which can take up a first position, wherein the stopping means prevent the resetting of the leaf springs, and a second position wherein the stopping means permit the leaf springs to perform a pivoting movement corresponding to the movement performed by the blocking means to which a respective leaf spring is connected.

6. The device of claim 5, wherein the leaf spring after having performed a pivoting movement takes up a position on the opposite side of the stopping means.

7. The device of claim 5, wherein the arm receives its reciprocal movement by means arranged on the main shaft of the machine.

8. The device of claim 5 wherein the arm cooperates with a fixation bracket arranged to fix the rockable links when the arm is in its second position.

t l I I I 

1. A device for preventing blocking means in a business machine from assuming a second position which is separated from a first position comprising at least one pivotable resilient means which is connected to the blocking means a stopping means arranged in the path of movement of the resilient means and mounted so that when the blocking means is affected to take up the second position the resilient means biases it to bear against one side of said stopping means and which stopping means restores the blocking means when the mentioned affection ceases.
 2. The device of claim 1, wherein there are a plurality of blocking means and wherein certain of the blocking means cooperate with each other via rockable links.
 3. The device of claim 1 wherein the blocking means when they are in certain positions block certain keys, positioned on the keyboard of the machine, against depression.
 4. The device of claim 2 wherein the resilient means consist of leaf springs which are fixed to links.
 5. The device of claim 4 wherein the stopping means are formed on an arm which is capable of performing a reciprocal movement and which can take up a first position, wherein the stopping means prevent the resetting of the leaf springs, and a second position wherein the stopping means permit the leaf springs to perform a pivoting movement corresponding to the movement performed by the blocking means to which a respective leaf spring is connected.
 6. The device of claim 5, wherein the leaf spring after having performed a pivoting movement takes up a position on the opposite side of the stopping means.
 7. The device of claim 5, wherein the arm receives its reciprocal movement by means arranged on the main shaft of the machine.
 8. The device of claim 5 wherein the arm cooperates with a fixation bracket arranged to fix the rockable links when the arm is in its second position. 